DESC:VARIABLE FLUX MACHINE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202221075286 filed on 25/12/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to an electric motor. Particularly, the present disclosure relates to a variable flux electric motor.
BACKGROUND
Permanent magnet motors are widely used in multiple industrial and automotive applications due to the offering of unique combination of inherent high torque/power density and high efficiency. Such motors utilize the high energy content of permanent magnetic materials to generate magnetic fields. The excellent control characteristics such as precise speed and torque control make the permanent magnet motors suitable for applications requiring high precision. Thus, the aforesaid motors emerge as competitive candidates in traction applications. Furthermore, the permanent magnet motor provides a simple structure and reliable operation in applications.
However, in conventional permanent magnet motors, the constant magnetic flux developed inside causes the motor's back electromotive force to become linear with speed, resulting in a linear speed to torque relationship. The increased back emf at higher speed results in increased losses during peak power production reduces the efficiency of operation and performance of the permanent magnet motor at peak power production. Moreover, the linear speed to torque relationship restricts the motor's operating range under various loads and thus limits the applications of permanent magnet motors in spaces demanding a wider combination range of speed and torque.
Conventionally, the flux weakening techniques application in stator windings of permanent magnet motors enable the adjustments in the magnetic flux to suit varying operational requirements such as variable speeds or/and high torque at high speeds. However, such technique sacrifices considerable amount of torque output. In addition, the heat generation within the motor increases thereby limiting the efficiency of operation.
Therefore, there exists a need for an electric motor that overcomes the one or more problems as aforementioned.
SUMMARY
An object of the present disclosure is to provide a permanent magnet motor with a variable flux.
In accordance with the first aspect of the present disclosure, there is provided a variable flux permanent magnet motor comprising a stator assembly and a rotor assembly. The rotor assembly comprises a plurality of rotor teeth, a plurality of permanent magnets, and a plurality of rotor coils. Each of the rotor teeth comprises a face and an elongated portion. The face receives at least one permanent magnet of the plurality of permanent magnets. The elongated portion receives at least one rotor coil of the plurality of rotor coils.
The present disclosure provides a variable flux electromagnetic motor. The motor as disclosed in the present disclosure is advantageous in terms of providing a nonlinear speed to torque characteristics. The disclosed motor is versatile for a wider range of applications arising from enlargement of operational range of motor in terms of torque-speed characteristics, under varying load conditions. Moreover, the disclosed motor is advantageous in terms of providing more efficient operation over a broader range of speeds and loads. The disclosed motor provides for desired variable flux along with improved power density. Furthermore, the disclosed motor provides a combination of high efficiency and easily adjustable air-gap field by hybrid excitation in rotor assembly. Advantageously, the disclosed motor has minimal cogging torque at the startup as the strength of the magnetic field within the motor can be varied using the coils present in the rotor assembly. Beneficially, the power source connected to the rotor coils supply controlled power to the rotor coils to generate variable flux along with the flux generated from the permanent magnets of the rotor assembly. Due to the combination of the variable flux generated by the rotor coils and the flux generated from the permanent magnets of the rotor assembly, the combined flux is varied. This variable flux when interacts with the electromagnetic flux generated by the stator coils produce variable torque to speed characteristics.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 illustrates an exploded view of a variable flux permanent magnet motor, in accordance with an embodiment of the present disclosure.
FIG. 2 illustrates an exploded view of power supply components of rotor assembly, in accordance with an embodiment of the present disclosure.
FIG. 3 illustrates a perspective view of rotor tooth, in accordance with an embodiment of the present disclosure.
FIG. 4 illustrates a sectional view of rotor assembly, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a permanent magnet variable flux motor and is not intended to represent the only forms that may be developed or utilized. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings which are shown by way of illustration-specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “electric motor”, “motor” and “variable flux permanent magnet motor” are used interchangeably and refer to an electromagnetic machine with hybrid excitation in rotor to produce a variable magnetic flux, along with electrical excitation in stator, thereby converting the electrical energy into rotational motion of the shaft.
As used herein, “stator assembly” and “stator” are used interchangeably and refer to the stationary part of a motor that carries the windings to create the electromagnetic field in the stator for interaction with the rotor. The stator includes a core made of ferromagnetic material, typically laminated steel, and multiple windings to produce a magnetic flux when energized by an electric current.
As used herein, the terms ‘rotor assembly’ and ‘rotor’ are used interchangeably and refer to a rotating member of the motor that develops the variable magnetic flux in the rotor, to interact with the stator's electromagnetic field to develop a net magnetic flux in the air gap.
As used herein, the terms ‘rotor teeth’ and ‘plurality of rotor tooth’ are used interchangeably and refer to a segment of the rotor to simultaneously hold the conductive windings and permanent magnet. The rotor teeth is usually made up of silicon steel, iron cobalt alloys and soft magnetic composites.
As used herein, the term ‘face’ of the rotor tooth refers to the outer circumferential area of the rotor tooth exposed to stator, to accommodate the permanent magnet to direct the fixed magnetic flux in radial direction.
As used herein, ‘rotor coil’ and ‘plurality of rotor coils’ refers to the arrangement and configuration of conductive wire within the rotor tooth to develop the variable magnetic flux within the rotor assembly. The arrangement includes various patterns, such as concentric wires, distributed wires, or any other configuration that facilitates the generation of magnetic fields. The material of the coils includes copper, aluminum, or other conductive materials. The coils are designed to optimize efficiency, torque, and overall motor performance of the motor.
As used herein, the term ‘elongated portion’ refers to side edges of the rotor tooth extending radially, configured to accommodate the rotor coil from one end towards another end of the elongated portion. The elongated portion guides the magnetic flux lines towards the air gap in concentrated and uniform manner.
As used herein, the terms ‘permanent magnet’ and 'plurality of permanent magnets’, are used interchangeably and refer to pieces of permanent magnets accommodated on the face for generating a fixed magnetic flux in the rotor tooth. The magnet are made of materials that have a natural magnetic field such as alnico, ferrite, neodymium iron boron and samarium cobalt. Each magnet is made up of similar material for obtaining the uniform distribution of the fixed magnetic flux inside the motor.
As used herein, the terms ‘motor shaft’ refers to a hollow shaft on which the rotor assembly are mounted through at least one bearing. The shaft is the rotating part of the motor that transfers the power output from the rotor assembly to the external load. The bearing enables the smooth rotation of the shaft. The shaft is made of a strong as well as lightweight material, such as steel or aluminium.
As used herein, the terms ‘slip ring’ refers to an electrical component usually in form of a ring shape to provide circuit path for transferring electrical power from the external power source to the rotor coils. The slip rings are made up of electrically conductive material such as copper and silver. The rings rotates with the rotor assembly during the operation of the motor.
As used herein, the terms ‘insulator ring’ refers to the non-conductive ring shaped component accommodated in between the adjacent slip rings to ensure proper electrical isolation of the adjacent slip rings for establishing the circuit path for the continuous transfer of electrical power across the rotor coils.
As used herein, the term ‘carbon brush’ refers to a component to maintain continuous physical contact with slip rings to enable the transfer of power to reach slip rings. The brushes ensure a consistent and efficient transfer of electrical power to the sliprings.
As used herein, the terms ‘spring’ refers to a mechanical component designed to exert sufficient pressure on the carbon brush to maintain continuous contact of the carbon brush with the slip ring, during the operation of the motor. The springs typically exhibit elastic properties, allowing them to deform reversibly during motor’s operation and return to their original shape after the switching off of the motor.
As used herein, the terms ‘power source’ refers to an electrical source to supply the electrical power to the carbon brush. The power source serves as the primary source of electrical energy to initiate and sustain the functionality of the rotor, enabling the conversion of electrical energy into variable magnetic flux.
As used herein, the terms ‘controller’ refers to an electronic device to regulate and manage the supply of electrical power that is directed to the rotor coils of the motor. The controller employs various control algorithms, feedback mechanisms, sensors, and processing units to interpret input signals and execute commands, thereby providing for the precise delivery of electrical energy.
As used herein, the terms ‘plurality of stator teeth’, and ‘stator teeth’ are used interchangeably and refer to a stator slot wedge that simultaneously holds the conductive windings in the slot and locates the teeth with respect to each other. The stator tooth is in the form of a protrusion from the surface of the stator.
As used herein, the terms ‘motor casing’ refers to the housing or enclosure usually in form of an outer shell of the electric motor for providing a protective and structural enclosure for the motor's internal components, such as the rotor coils, stator coils and permanent magnets. The casing provides for physical protection against external environmental factors, mechanical stresses, and contaminants. The casing is typically constructed from durable and insulating materials such as metals, plastics, composites, or alloys. The casing includes design features, such as cooling fins, vents, or heat sinks, to dissipate heat generated during motor operation, thereby ensuring optimal performance and longevity of the motor.
Figure 1, in accordance with an embodiment, describes an exploded view of a variable flux permanent magnet motor 100 comprising a stator assembly 102 and a rotor assembly 104. The rotor assembly 104 comprises a plurality of rotor teeth 106, a plurality of permanent magnets 108, and a plurality of rotor coils 110. Each of the rotor teeth 106 comprises a face 106a and an elongated portion 106b. The face 106a receives at least one permanent magnet 108 of the plurality of permanent magnets 108. The elongated portion 106b receives at least one rotor coil 110 of the plurality of rotor coils 110.
The motor 100 is advantageous in terms of providing a nonlinear speed to torque characteristics. The motor 100 is versatile for a wider range of applications. Beneficially, the 100 has a wider operational range due to variable magnetic flux generating a variable torque-speed characteristics under varying load conditions. Moreover, the motor 100 is advantageous in terms of providing more efficient operation over a broader range of speeds and loads due to precise control on the magnetic flux. The motor 100 provides for desired variable flux along with improved power density as required during operation. The variable flux is achieved by providing regulated hybrid excitation of rotor coils 110 of permanent magnet motor 100. The regulation of the hybrid excitation is attained through control on the magnitude and direction of the current in the rotor coils 110. Furthermore, the motor 100 provides a combination of high efficiency and easily adjustable air-gap field by hybrid magnetic field generation in rotor assembly 104. Advantageously, the motor 100 has minimal cogging torque at the startup as the strength of the magnetic field from the rotor assembly 104 can be varied.
In an embodiment, the motor 100 comprises motor casing 112, wherein motor casing 112 encloses the rotor assembly 104 and stator assembly 102. It is to be understood that the motor casing 112 protects the rotor assembly 104 and stator assembly 102 against external elements like dust, moisture, and physical damage. Beneficially, the motor casing 112 provides structural support to the motor shaft 116 and stator assembly 102.
In an embodiment, the motor casing 112 comprises a power source 114 on an inner radial surface. It is to be understood that the power source 114 accommodated on the inner radial surface of the motor casing 112 is direct current power source 114. Beneficially, the direct current power source 114 provides for supply of the electrical power in the rotor assembly 104. In an alternative embodiment, the power source 114 accommodated on the inner radial surface of the motor casing 112 is alternating current power source 114.
In an embodiment, the motor 100 comprises a controller to control electric power supplied to the plurality of rotor coils 110. It is to be understood that the control of the supply of the electric power is established by adjusting the electrical current flowing through the rotor coils 110.
In an embodiment, the stator assembly 102 comprises a plurality of stator teeth 102a, wherein each of the stator teeth 102a comprises stator coils. It is to be understood that the plurality of stator teeth 102a are included in the stator assembly 102 to accommodate the stator coils. Beneficially, the stator coils provides for generating the magnetic flux, when supplied with alternating current power supply. Beneficially, the stator teeth 102a provides for shaping the magnetic field by guiding and concentrating the magnetic flux towards the rotor assembly 104.
In an embodiment, the rotor coils 110 generate a varying magnetic flux along with the fixed flux of the plurality of permanent magnets 108 to interact with the magnetic flux generated by the stator coils for rotating the rotor assembly 104. It is to be understood that the rotor coils 110 generate the varying magnetic flux that varies in accordance with the magnitude and direction of the supplied electrical power. It is to be understood that the fixed flux is generated by the plurality of permanent magnets 108. Beneficially, within the motor 100 the mutual interaction is established between the varying magnetic flux, the fixed flux and the magnetic flux in order to produce torque on the rotor assembly 104.
Figure 2, in accordance with an embodiment, describes an exploded view of power supply components of rotor assembly 104. In an embodiment, the motor 100 comprises a motor shaft 116, and wherein the rotor assembly 104 is mounted on the motor shaft 116. It is to be understood that the motor shaft 116 provides support and stability to the rotor assembly 104. Beneficially, the motors shaft 116 provides for the accurate alignment and positioning of the rotor assembly 104 within the stator assembly 102.
In an embodiment, the motor 100 comprises at least one pair of slip ring 118 mounted on the motor shaft 116. It is to be understood that the slip rings 118 are provided to act as an intermediate medium for the transfer of electric power to the rotor coils 110.
In an embodiment, the motor 100 comprises a pair of carbon brushes 120, and wherein the carbon brush 120 comprises a spring 122 in contact with the power source 114. It is to be understood that the spring 122 is maintained in a compression state during the operation of the motor 100, for applying a consistent and proper pressure on the carbon brushes 120 to enable the delivery of electric power to the rotor assembly 104.
In an embodiment, each of the carbon brush 120 is mounted on the slip rings 118 to supply power received from the power source 114. It is to be understood that the mounting of the carbon brushes 120 is done properly over the exposed surface of the slip rings 118 to establish continuous physical contact with the slip rings 118 during the rotation of the rotor assembly 104, for transfer of the electric power continuously to the slip rings 118. Beneficially, the establishment of physical contact provides for the development of electrical path between the power source 114 and the slip rings 118.
In an embodiment, the motor 100 comprises an insulation ring 124 placed between the adjacent slip ring 118 mounted on the motor shaft 116. It is to be understood that the insulation ring 124 provides for electrical insulation thereby avoiding direct electrical contact between the adjacent slip rings 118. Beneficially, the presence of the insulation ring 124 provides for establishing the appropriate transfer of electric power supply in the rotor coils 110.
Figure 3, in accordance with an embodiment, describes a perspective view of rotor teeth 106. Each of the rotor teeth 106 comprises a face 106a, wherein the face 106a receives at least one permanent magnet 108 of the plurality of permanent magnets 108. Each of the rotor teeth 106 comprises an elongated portion 106b, wherein the elongated portion 106b receives at least one rotor coil 110 of the plurality of rotor coils 110.
In an embodiment, the plurality of rotor coils 110 are connected in series with each other. It is to be understood that the series connection of rotor coils 110 provides for supplying same current to each rotor coil 110. Beneficially, the aforesaid connection provides for establishment of uniform torque distribution in the rotor assembly 104.
Figure 4, in accordance with an embodiment, describes a sectional view of rotor assembly 104, in accordance with another aspect of the present disclosure. In an embodiment, at least one rotor coil 110 of the plurality of rotor coil 110 is connected to the pair of slip ring 118. It is to be understood that the connection provides for transferring the electric power from the pair of slip rings 118 to the rotor coils 110. Beneficially, the aforesaid connection provides for a continuous electrical pathway while the motor 100 is in operation.
In an embodiment, the plurality of rotor coils 110 receive the power from the power source 114 via the slip rings 118 and carbon brushes 120. It is to be understood that the carbon brushes 120 and the slip rings 118 are provided to carry power in succession to reach the rotor coils 110.
In an embodiment, the variable flux permanent magnet motor 100 comprises the stator assembly 102 and the rotor assembly 104. The rotor assembly 104 comprises the plurality of rotor teeth 106, the plurality of permanent magnets 108, and the plurality of rotor coils 110. Each of the rotor teeth 106 comprises the face 106a and the elongated portion 106b. The face 106a receives at least one permanent magnet 108 of the plurality of permanent magnets 108. The elongated portion 106b receives the at least one rotor coil 110 of the plurality of rotor coils 110. Furthermore, the motor 100 comprises a motor casing 112, wherein the motor casing 112 encloses the rotor assembly 104 and the stator assembly 102. Furthermore, the motor casing 112 comprises a power source 114 on an inner radial surface. Furthermore, the motor 100 comprises a motor shaft 116, and wherein the rotor assembly 104 is mounted on the motor shaft 116. Furthermore, the motor 100 comprises at least one pair of slip ring 118 mounted on the motor shaft 116. Furthermore, the motor 100 comprises a pair of carbon brushes 120, and wherein each of the carbon brush 120 comprises a spring 122 in contact with the power source 114. Furthermore, each of the carbon brush 120 is mounted on the slip rings 118 to supply power received from the power source 114. Furthermore, the motor 100 comprises an insulation ring 124 placed between the adjacent slip ring 118 mounted on the motor shaft 116. Furthermore, the plurality of rotor coils 110 are connected in series with each other. Furthermore, the at least one rotor coil 110 of the plurality of rotor coil 110 is connected to the pair of slip ring 118. Furthermore, the plurality of rotor coils 110 receive the power from the power source 114 via the slip rings 118 and carbon brushes 120. Furthermore, the motor 100 comprises a controller to control the power supplied to the plurality of rotor coils 110. Furthermore, the stator assembly 102 comprises a plurality of stator teeth 102a, wherein each of the stator teeth 102a comprises stator coils. Furthermore, the rotor coils 110 generate a varying magnetic flux along with the fixed flux of the plurality of permanent magnets 108 to interact with the magnetic flux generated by the stator coils for rotating the rotor assembly 104.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:We Claim:
1. A variable flux permanent magnet motor (100), the motor (100) comprises:
- a stator assembly (102);
- a rotor assembly (104) comprising a plurality of rotor teeth (106), a plurality of permanent magnets (108), and a plurality of rotor coils (110), wherein each of the rotor teeth (106) comprises:
a face (106a), wherein the face (106a) receives at least one permanent magnet (108) of the plurality of permanent magnets (108); and
an elongated portion (106b), wherein the elongated portion (106b) receives at least one rotor coil (110) of the plurality of rotor coils (110).
2. The motor (100) as claimed in claim 1, wherein the motor (100) comprises a motor casing (112), wherein the motor casing (112) encloses the rotor assembly (104) and the stator assembly (102).
3. The motor (100) as claimed in claim 1, wherein the motor casing (112) comprises a power source (114) on an inner radial surface.
4. The motor (100) as claimed in claim 1, wherein the motor (100) comprises a motor shaft (116), and wherein the rotor assembly (104) is mounted on the motor shaft (116).
5. The motor (100) as claimed in claim 1, wherein the motor (100) comprises at least one pair of slip ring (118) mounted on the motor shaft (116).
6. The motor (100) as claimed in claim 5, wherein the motor (100) comprises a pair of carbon brushes (120), and wherein each of the carbon brush (120) comprises a spring (122) in contact with the power source (114).
7. The motor (100) as claimed in claim 6, wherein each of the carbon brush (120) is mounted on the slip rings (118) to supply power received from the power source (114).
8. The motor (100) as claimed in claim 5, wherein the motor (100) comprises an insulation ring (124) placed between the adjacent slip ring (118) mounted on the motor shaft (116).
9. The motor (100) as claimed in claim 1, wherein the plurality of rotor coils (110) are connected in series with each other.
10. The motor (100) as claimed in claim 1, wherein the at least one rotor coil (110) of the plurality of rotor coil (110) is connected to the pair of slip ring (118).
11. The motor (100) as claimed in claim 1, wherein the plurality of rotor coils (110) receive the power from the power source (114) via the slip rings (118) and carbon brushes (120).
12. The motor (100) as claimed in claim 1, wherein the motor (100) comprises a controller to control the power supplied to the plurality of rotor coils (110).
13. The motor (100) as claimed in claim 1, wherein the stator assembly (102) comprises a plurality of stator teeth (102a), wherein each of the stator teeth (102a) comprises stator coils.
14. The motor (100) as claimed in claim 1, wherein the rotor coils (110) generate a varying magnetic flux along with the fixed flux of the plurality of permanent magnets (108) to interact with the magnetic flux generated by the stator coils for rotating the rotor assembly (104).